As shown in FIG. 4, a conventional multi-layer board is formed with resin layers. For example, on a first surface 1, a patterned is formed, and an electronic component 2 is mounted. The electronic component 2 is conducted to a second surface 4, third surface 5 or fourth surface 6 with a through hole 3 in order to be connected to a component such as an inductor formed on the surface 4, 5 or 6. Intervals between any of the first surface 1 through the fourth surface 6 are filled with a resin 7.
The conventional multi-layer board consisting of the resin layers, upon having the inductor formed thereon, shrinks with heat due to a temperature change, thus causing a characteristic such as an inductance to vary.